1. Field of the Invention
The present invention relates to a vehicle interference prevention device for preventing vehicles from interfering with one another in situations where a plurality of vehicles are traveling over travel routes.
2. Description of the Related Art
At large work sites such as rock quarries and mining operations, control of a plurality of unmanned vehicles, such as unmanned dump trucks, used to perform operations such as hauling earth is typically accomplished through a vehicle monitoring system in which a monitoring station is set up as a base station, with all of the unmanned vehicles being managed and monitored by this monitoring station.
Vehicle monitoring systems of this type known in the art include the systems disclosed in Japanese Patent Application Laid-Open No. 63-150710 (hereinbelow referred to as Citation 1) and Japanese Patent Application Laid-Open No. 10-69599 hereinbelow referred to as Citation 2), as well as in the Applicant""s co-pending Japanese Patent Application No. 9-27960 (hereinbelow referred to as Citation 3), Japanese Patent Application No. 9-36324 (hereinbelow referred to as Citation 4), and Japanese Patent Application No. 9-86612 (hereinbelow referred to as Citation 5).
According to the system disclosed in Citation 1, there is provided a predetermined operation whereby, in the event of a risk of collision between any of a plurality of unmanned vehicles, the unmanned vehicles at risk for collision may exchange necessary information with each other via communication devices so as to avoid collision.
According to the system disclosed in Citation 2, lane-change sensors provided with optical means are embedded in the road surface of a highway at the boundary between an automatically guided vehicle lane L1 and an adjacent travel lane L2, so that in the event that a vehicle traveling in lane L2 should enter lane L1 (i.e., make a lane change) the control system, on the basis of signals from the lane-change sensors, will control any automatically guided vehicle traveling behind the vehicle which has entered the lane in such a way as to provide greater distance between vehicles.
According to the system disclosed in Citation 3, long-range (e.g. VHF) communication devices are provided to a plurality of unmanned vehicles and to a monitoring station, the plurality of unmanned vehicles being provided also with short-range (e.g. SS transmission) communication devices, whereby travel instruction data may be transmitted from the monitoring station to the unmanned vehicles via the long-range communication devices, while the unmanned vehicles may exchange vehicle position data among themselves using the short-range communication devices, thereby allowing for monitoring of positional relationships among the vehicles.
According to the system disclosed in Citation 4, an arranged route of travel is divided into a plurality of segments, and a plurality of vehicles, via communication devices provided thereto, transmit to a monitoring station vehicle position data and the like which has been ascertained by position-measuring devices, transmitting this information each time that a vehicle reaches a segment boundary on an arranged route of travel, whereby the monitoring station may ascertain positional relationships among a plurality of vehicles in each segment, and monitor and control the plurality of vehicles with reference to these positional relationships. In order to prevent interference between manned vehicles and unmanned vehicles, for example, the monitoring station will forcibly halt or decelerate a manned vehicle in the event that the manned vehicle does not obey instruction data (data instructing deceleration, a stop, etc.).
According to the system disclosed in Citation 5, vehicle position data is exchanged via communication devices among a plurality of vehicles, for example, manned vehicles and unmanned vehicles, whereby vehicles, on the basis of vehicle position data for other vehicles, perform control so as to prevent interference among vehicles. In this system, in the event of a determination, made on the basis of vehicle position data exchanged between a manned vehicle and an unmanned vehicle, that the vehicles are interfering with one another, control is effected such that the unmanned vehicle comes to an emergency stop while the manned vehicle is decelerated so as to prevent interference among the vehicles.
The systems disclosed in Citation 1 and Citation 3, however, are directed to preventing interference among unmanned vehicles and make no mention whatsoever of preventing interference among manned vehicles and unmanned vehicles.
The system disclosed in Citation 2 employs a stationary installation (i.e. a highway), detecting vehicles entering the lane traveled by automatically guided vehicles and decelerating the automatically guided vehicles. However, the use of a stationary installation entails numerous initial outlays associated with construction of the installation. Further, it is difficult to adapt such a system to a mine, where travel routes change frequently.
While it is possible to embed lane change sensors along the course of an asphalt highway, this approach is not feasible for mine roads, which are maintained by graders.
Specifically, the off-road dump trucks used in mining operations, even those of ordinary size, have vehicle weights of several hundred tons when loaded, while larger vehicles can weigh in at close to 700 tons. Even if lane change sensors were embedded in an asphalt travel path (roadway), the asphalt road would not be able to bear the weight of the vehicle. Also, lane change sensors embedded in the roadway would be crushed by the weight of the vehicle.
Accordingly, it is common practice in mining operations and the like to pave roads with gravel. Assuming that lane change sensors were embedded in road paved with gravel or the like, the need to periodically maintain the pavement through grading poses the problem of equipment, such as lane change sensors, embedded in the pavement being crushed during the grading operation.
Further, lane change sensors can detect a vehicle only after it has entered a lane; while this presents no particular problem in the case of highways and other roadways with minimal cross-traffic, in mining operations, which typically have a complex web of routes, there exists a risk, depending on the condition of travel of a vehicle, that the vehicle will be detected only as it approaches an intersection. This means that where the risk exists that traveling vehicles will interfere (collide) in proximity to an intersection, the delay in control to prevent collision may result in collision of the vehicles.
The system disclosed in Citation 4 assumes travel of manned vehicles over a predetermined course (prearranged travel route) in a manner analogous to unmanned vehicles, with monitoring and control being performed from a central monitoring station, and as such is difficult to implement in situations where the human operator of a vehicle may choose, for example, to make a U-turn mid-course or otherwise change course from time to time. Further, manned vehicles are driven by human operators, and some operators may find disagreeable the approach of travel to a predetermined destination selected in accordance with the operation. Forcible introduction of a system that ignores operator preference will have a negative impact on operations.
According to the system disclosed in Citation 5, interference among vehicles may be prevented even in situations where manned vehicles coexist with unmanned vehicles. However, depending on communication conditions, it may occur that an unmanned vehicle cannot receive vehicle position data from a manned vehicle; in such instances, there exists the risk of a delay in the determination process for interference between vehicles, resulting in an inability exercise proper control to prevent interference between vehicles.
For manned vehicles, in instances of interference between vehicles, while a Reduce Speed command sent from the unmanned vehicle is displayed on the display screen of a display device, it is not possible to ascertain the positional relationship vis-xc3xa1-vis the other vehicle. That is, if the position of one""s vehicle relative to the other vehicle could be displayed in real time, it would be possible to determine before the fact if a given current course of travel is likely to result in interference between vehicles, for example, thereby making it possible to avoid interference between vehicles. This is not possible with the system disclosed in Citation 5, however.
The systems disclosed in Citation 1 and Citations 3 to 5 presume that position-measuring devices and communication devices are provided to all vehicles (both unmanned vehicles and manned vehicles) operating in a large work site such as a mining operation, but providing position-measuring devices and communication devices to all vehicles requires a significant initial outlay. There are also various costs associated with equipping vehicles that do not enter the mine, such as repair vehicles, with position-measuring devices and communication devices.
Position-measuring devices and communication devices that are used infrequently have increased likelihood of malfunction when it is attempted to operate the device. While it is possible to design position-measuring devices and communication devices to be readily attachable and detachable, in some instances there may be an insufficient number of devices.
From the standpoint of preventing vehicle interference, that is, for reasons of vehicle safety, vehicles lacking position-measuring devices and communication devices due to malfunction or a shortage thereof cannot be employed. This means that despite the availability of vehicles to do the work, the vehicle resources cannot be used effectively.
In the vehicle monitoring systems of the Citations cited above, the radio waves used for communications of the short-range (e.g. SS transmission) communication devices used for communication among vehicles can only travel over short distances (from 100 m to 1 km), and in large-scale mining operations involving large distances between vehicles and large numbers of vehicles (50 to 100, for example), it is not possible for all vehicles to know the current positions of other vehicles.
With the conventional vehicle monitoring systems described above, while long-range (10 km to 20 km) communications are possible if long-range (e.g. VHF) communication devices are used, slow transmission speed (9600 bps) creates the problem of inability to constantly be apprised of the current locations of a multitude of vehicles. Since large amounts of data are transmitted to the monitoring station from the multitude of vehicles, the volume of data being transmitted is quite large. Since the communications format entails slow transmission speeds, the communications circuit becomes complicated and the communications circuit becomes overloaded, resulting in inability in actual practice to manage and monitor vehicles.
Where it is attempted to address this problem by employing short-range communication devices capable of higher transmission speeds (256 kbps) for communication among vehicles, while it becomes possible to transmit very large amounts of data rapidly, the limited range of the radio waves makes it impossible to provide full communications coverage over the entirety of large work site. Thus, of the vehicles spread over entirety of a large work site, it will not be possible for a vehicle to communicate with another vehicle located a distance away that exceeds the short range transmission range (100 m to 1 km, for example), and hence there will be no way to determine the current position of this other vehicle.
Accordingly, in large-scale mining operations involving large distances between vehicles and large numbers of vehicles, it has not been possible for all vehicles to be constantly apprised of the current locations of other vehicles.
With the foregoing in view, it is an object of the present invention to provide a vehicle interference prevention device that, by computing a range of possible locations of a vehicle taking into consideration the time at which the location of the vehicle is measured, can safely predict the location of the vehicle, even with minimal frequency of radio contact, and prevent interference among unmanned vehicles or manned vehicles over an entire large work site.
According to the invention of claim 1, the object is achieved through a vehicle interference prevention device for preventing interference among vehicles where a plurality of vehicles are traveling over a travel route, wherein each of the plurality of vehicles comprises:
measuring means for measuring a position of its own vehicle;
communication means for exchanging with other vehicles, in a wireless communications format, position information indicating the position of its own vehicle, as measured by the measuring means;
estimating means for estimating a likelihood of interference between its own vehicle and other vehicle on the basis of position information for the other vehicle received via the communication means, time information indicating a reception time at which the position information is received, and the position information for its own vehicle; and
control means for performing a preset control routine in the event that interference is predicted by the estimating means, so as to avoid interference with the other vehicle.
According to the second invention, in the vehicle interference prevention device of the first invention,
the communication means comprises:
means for transmitting and receiving vis-xc3xa1-vis other vehicles, in a wireless communications format, position information indicating vehicle position, as measured by its own measuring means, and time information indicating a time of measurement of the vehicle position or time information indicating a time of transmission of the position information; and
the estimating means comprises:
means for estimating the likelihood of interference between its own vehicle and other vehicle on the basis of the position information for the other vehicle received via the transmitting/receiving means, the time information for either the measurement time or the transmission time, and the position information for its own vehicle.
According to the third invention, in the vehicle interference prevention device of the first invention or the second invention,
the estimating means comprises:
first estimating means for estimating, on the basis of the position information and the time information for other vehicle received via the communication means, a future position of the other vehicle at a point in time coming a predetermined time interval after the time, or a range of movement of the other vehicle;
second estimating means for estimating from its current position on the basis of position information for its own vehicle a future position of its own vehicle at a point in time coming a predetermined time interval later, or a range of movement of its own vehicle; and
decision means for deciding if the future position or range of movement of the other vehicle estimated by the first estimating means overlaps the current position or future position of its own vehicle estimated by the second estimating means.
According to the fourth invention, in the device of first invention, second invention, or third invention, each of the plurality of vehicles further comprises processing means that, during power-on of its own vehicle, notifies other vehicle that its own vehicle has started up, and in the event that no response to the notification is received by its own communication means, makes a determination that the communication means of the other vehicle is not functioning normally, and places its own vehicle in standby mode at its current position.
The first through third invention are now described making reference to the attached drawings.
To prevent interference among vehicles, the range of possible locations for other manned vehicles can be calculated by an unmanned vehicle or manned vehicle in the following manner, for example.
Method 1: Circle Computation Method
Referring to FIG. 6, an own vehicle (either an unmanned vehicle or a manned vehicle), for example, unmanned vehicle 10, uses the last-acquired position data P (position at a certain point in time) for a manned vehicle (other vehicle) for example, manned vehicle 11), acquired (received) via inter-vehicle communication device 6 shown in FIGS. 2, 3 and 4 as the basis for computing a circle 70 having position P as its center and having a radius r equal to the distance traveled at maximum speed from point P to a predetermined future point in time, and designates the area within this circle 70 on prearranged travel route 60 as range of possible locations for manned vehicle 11.
Method 2: Course Computation Method
Referring to FIG. 7, an own vehicle (either an unmanned vehicle or a manned Vehicle), for example, unmanned vehicle 10, uses the last-acquired position data P (position at a certain point in time) and direction information (direction of progress indicated in the figure by xe2x86x92) for a manned vehicle acquired (received) via inter-vehicle communication device 6 as the basis for computing positions on an prearranged travel route 60 course), for example, position 60a and position 60b on prearranged travel route 60xe2x80x94assuming movement of the manned vehicle at maximum speed from point P to a predetermined future point in timexe2x80x94and designates the area between point P and positions 60a, 60b (crosshatched area in the figure) 71 as the range of possible locations for the manned vehicle.
The own vehicle respectively computes, for example, 5-second-ahead and 15-second-ahead ranges of possible locations for itself and for the other vehicle, and determines for each of these whether these range of possible locations interfere with each other. In the event that the 15-second-ahead range of possible locations interfere, the vehicle (unmanned vehicle 10, for example) makes a determination as to whether the reception time of position data for the other vehicle is older than predetermined time interval (30 seconds or more, for example) (STEP 304 in FIG. 11), and where this predetermined time interval (30 seconds, for example) has already passed, the vehicle at risk for interference is requested directly for position information by UHF transmission via the inter-vehicle communication device 6 shown in FIGS. 2, 3 and 4 (STEP 305 in FIG. 11).
On the other hand, in the event that the 5-second-ahead range of possible locations interfere, travel of the vehicle (unmanned vehicle 10, for example) is controlled by a vehicle control device 44 so as to stop as quickly as possible (STEP 406).
According to the first to third inventions described above, a vehicle, on the basis of position information for itself, position information transmitted to it from another vehicle, and time information (either the reception time, position measurement time, or transmission time for this position information), estimates the likelihood of interference between itself and another vehicle, and performs appropriate control on the basis of this estimate so as to avoid interference between the vehicles.
Specifically, from the current position of other vehicle, an estimate is made of a range of movement for the other vehicle at a point in time having passed a predetermined time interval form the time based on the time information, thus allowing a determination to be made as to whether the estimated range of movement of the other vehicle interferes with its own vehicle, the time interval between transmissions of position data over long distances can be increased, thereby reducing the load on the communications circuit.
The fourth invention is now described making reference to FIG. 9.
At power-on, a vehicle controller 55 provided to manned vehicle 11 enters a malfunction detection mode, at which time a Power-on signal and Vehicle ID for manned vehicle 11 are transmitted to a monitoring station 20 through UHF transmission via a monitoring station/vehicle communication device 5 (S11). Through UHF transmission via a monitoring station/vehicle communication device 23, monitoring station 20 transmits to all vehicles powered-up at that time (unmanned vehicles 10 and 12 in this example) the Vehicle ID for the newly powered-up manned vehicle 11 and a signal indicating that xe2x80x9cmanned vehicle 11 has powered upxe2x80x9d (S12). In the event that an acknowledging signal is received, for example, from unmanned vehicle 12 (S13) whereas no acknowledging signal is received from unmanned vehicle 10 after a predetermined time interval TA has passed, Warning information is transmitted to manned vehicle 11 (S14), and the same signal (namely, the same signal as in S12) is re-transmitted to both unmanned vehicles 10 and 12 or to the vehicle failing to respond, here, unmanned vehicle 10 (S15).
When manned vehicle 11 receives Warning information, it recognizes that the vehicle communication devices 5, 6 of some or all of the other vehicles currently in operation (traveling) are not functioning normally, and goes into standby at its current position.
According to the fourth invention, the processing means of a vehicle that has powered up transmits to other vehicles identifying information that identifies its own vehicle and notification that its own vehicle has powered up, and in the event that no response is received, recognizes that there is a malfunction with the communications means of the other vehicle or vehicles, and places its own vehicle in standby mode at its current position. In this way, the powered-up own vehicle will commence travel only after verifying that it is safe to do so, so as to avoid colliding or otherwise interfering with other vehicles.
According to the fifth invention, there is provided a vehicle interference prevention device having an unmanned vehicle comprising vehicle position-measuring means for measuring a position of its own vehicle and traveling over a travel route based on predetermined instruction data, a first manned vehicle having position-measuring means for measuring a position of its own vehicle, and a second manned vehicle traveling over the travel route guided by the first manned vehicle;
wherein the unmanned vehicle and the first manned vehicle each comprises communication means for transmitting and receiving predetermined information among themselves;
the first manned vehicle transmits to the unmanned vehicle via the communication means a mode which is either a guiding mode wherein the second manned vehicle is guided, or a non-guiding mode wherein the second manned vehicle is not guided; and transmits to the unmanned vehicle via the communication means position information indicating the vehicle position determined by the position-measuring means; and
the unmanned vehicle, in the event that the mode received via the communication means is the non-guiding mode, is controlled, on the basis of the position information from the first manned vehicle, in such a way as to avoid entering an area of a given range that includes a current position of the first manned vehicle; whereas in the case of the guiding mode, it is controlled, on the basis of the position information from the first manned vehicle, in such a way as to avoid entering the current position of the first manned vehicle and an area of a given range lying to a rear of the first manned vehicle.
According to the sixth invention, the vehicle interference prevention device of the fifth invention,
further comprises a monitoring station having transmitting/receiving means for transmitting and receiving predetermined information to and from the unmanned vehicle and the first manned vehicle; and
the monitoring station further comprises means for transmitting to the unmanned vehicle via the transmitting/receiving means instruction data designating as a permissible travel range over which travel is permitted an area on the travel route such that the most recent position of the unmanned vehicle, based on the position information measured by the vehicle position-measuring means and received via the transmitting/receiving means, does not interfere with a predicted range of motion for the first manned vehicle, as calculated on the basis of the most recent position information for the first manned vehicle received via the transmitting/receiving means.
According to the seventh invention, in the vehicle interference prevention device of the sixth invention, the transmitting means, in the event that the first manned vehicle is currently in the guiding mode, excludes from the permissible travel range a predicted range for the second manned vehicle that is obtained on the basis of the position information for the second manned vehicle based on the position information for the first manned vehicle, and transmits to the unmanned vehicle instruction data designating an area of this range as a new permissible travel range.
According to the eighth invention, in the vehicle interference prevention device of the fifth invention, the unmanned vehicle comprises:
measuring means for measuring the position of its own vehicle;
decision means for deciding, on the basis of the position information from the first manned vehicle received from the communication means and position information indicating the position of its own vehicle as measured by the measuring means, whether its own vehicle poses interference with the first manned vehicle or with an area of a predetermined range extending from the position of the manned vehicle; and
control means that, in the event that the decision means decides that interference is present, halts or decelerates its own vehicle.
The fifth through eighth inventions are now described making reference to FIGS. 16 and 17.
Let it be assumed that the vehicle computing a vehicle range of possible locations is an unmanned vehicle (unmanned vehicle 10, for example; in actual practice, it does not matter if the vehicle is a manned vehicle or unmanned vehicle), and that the other vehicle whose range of possible locations is being computed is a manned vehicle {escort vehicle (manned vehicle 11, for example) only, or an escort vehicle plus an escorted vehicle (such as a repair vehicle)}.
Methods for calculating a range of possible locations for a vehicle include the following two, for example.
Method 1: Circle Computation Method
Referring to FIG. 16, on the basis of position data indicating the last reported vehicle position P (latest position data), unmanned vehicle 10 designates as a range of possible locations for escort vehicle 11 a circle 80 of radius r equivalent to the distance over which the latter vehicle can travel at maximum speed from vehicle position P.
The range of possible locations for the escorted vehicle consists of an area defined by circle 80 and circles 81, 82 of radii equal to the distances traveled at maximum speed from a point P1, lying within a predetermined distance from position Pxe2x80x94which represents the last reported vehicle position for which information has been received from escort vehicle 11xe2x80x94defined as the escort area, and another point P2, respectively.
Method 2: Course Computation Method
Referring to FIG. 17, on the basis of position data indicating the last reported vehicle position P (latest position data) received via the inter-vehicle communication device 6, unmanned vehicle 10 computes positions 60a, 60b on prearranged travel route 60 assuming movement of the manned vehicle at maximum speed along the prearranged travel route up to a predetermined future point in time, and designates as the range of possible locations for the escort vehicle the area 90 on the prearranged travel route lying between these positions 60a, 60b and the last reported vehicle position P.
The range of possible locations for the escorted vehicle 11 is determined by computing positions on the travel route assuming travel at maximum speed from a point P1xe2x80x94lying within a predetermined distance defined as the escort area from position P which represents the last reported vehicle position for which information has been received from escort vehicle, and another point P2, respectively, and adding these to area 90, previously computed on the basis of point P.
Unmanned vehicle 10, which computes a range of possible locations for the manned vehicle in the preceding manner, is provided by monitoring station 20 with the Vehicle ID and mode information for the manned vehicle, as well as instruction data reflecting this mode information. Unmanned vehicle 10 is controlled by monitoring station 20 so as to prevent it from entering the range of possible locations for the manned vehicle.
Specifically, where the escort vehicle (manned vehicle 11) is in non-escort mode, unmanned vehicle 10 is controlled so as to prevent it from entering range of possible locations 80 computed using Method 1, or range of possible locations 90 computed using Method 2; whereas in escort mode, it is controlled so as to prevent it from entering range of possible locations 80 and range of possible locations 81, 82 computed using Method 1, or range of possible locations 90 and range of possible locations 91 computed using Method 2.
As will be apparent from the preceding description, according to the fifth through eighth inventions, a second manned vehicle lacking position-measuring means for measuring the position of its own vehicle and communication means for transmitting to an unmanned vehicle position data indicating the vehicle position determined thereby is guided by a first manned vehicle equipped with position-measuring means and communication means, whereby the manned vehicle lacking position-measuring means and communication means may be conducted safely about a large work site such as a mining operation.
In the event that the position-measuring means and communication means of a first manned vehicle should fail to function properly due to malfunction or the like, the first manned vehicle may nevertheless be conducted safely about a large work site guided by another first manned vehicle.
According to the ninth invention, there is provided a vehicle interference prevention device for preventing interference among a plurality of vehicles, including at least one manned vehicle, as they travel along a travel route, wherein each of the plurality of vehicles comprises:
measuring means for measuring a position of its own vehicle; and
communication means for exchanging with other vehicles position information indicating the vehicle position measured by the measuring means;
and the manned vehicle comprises:
processing means for calculating relative positional relationship of its own vehicle and other vehicle on the basis of position information for the other vehicle received via the communication means, and position information for its own vehicle; and
notifying means for notifying predetermined information depending on the relative positional relationship calculated by the processing means.
According to the tenth invention, in the vehicle interference prevention device of the ninth invention, wherein the notifying means comprises display means for visually displaying the relative positional relationship.
According to the eleventh invention, in the vehicle interference prevention device of the ninth invention or tenth invention, the notifying means provides a warning in the event that the relative positional relationship is such that its own vehicle and the other vehicle are in close proximity and interfering.
According to the twelfth invention, in the vehicle interference prevention device of the ninth invention, the plurality of vehicles further comprises:
transmitting/receiving means for exchanging with other vehicle time information indicating either of a time at which the vehicle position was measured by the measuring means of its own vehicle, or a time at which position information indicating this vehicle position was transmitted; and
all of the manned vehicles including at least one manned vehicle further comprise:
range estimating means for estimating, on the basis of position information for other vehicle received via its own communication means, and either time information for this position information indicating the time at which the position information was received by the communication means, or the time information having been transmitted by the other vehicle, a range of movement of other vehicle from a position based on the position information to another position at a point in time coming after a predetermined time interval has passed; and
display means for displaying the relative positional relationship calculated by the processing means, and for displaying the range of movement estimated by the range estimating means for the other vehicle in the positional relationship.
The ninth through twelfth inventions are now described making reference to FIGS. 6, 7, and 16-19.
The manned vehicle displays on the display screen of its display device 52a information pertaining to the range of possible locations for another manned vehicle or unmanned vehicle, as depicted in FIGS. 16 and 17, for example. Where the other vehicle is a manned vehicle, and it is further the case that the range of possible locations for the own vehicle and the range of possible locations for the other vehicle interfere, with the other vehicle expected to travel in the same direction over the prearranged travel route for the vehicle, there is issued Warning information to the effect that there is a risk of overtaking the other vehicle (STEP 706 in FIG. 18), whereas if the other vehicle is not traveling in the same direction, there is issued Alarm information warning of the risk of collision with the other vehicle (STEP 707 in FIG. 18).
Substantially identical processes are performed where the other vehicle is an unmanned vehicle (STEP 806, STEP 807 in FIG. 19).
Specific examples of the above-mentioned Warning information would be, for example, a display on the display screen of display device 52a to the effect that there is a risk of overtaking the other vehicle, or lighting up of the yellow light of indicator light 52b. A combination of the above is also possible. Specific examples of the above-mentioned Alarm information would be, for example, a display on the display screen of display device 52a to effect that there is a risk of collision with the other vehicle, for example; lighting up of the red light of indicator light 52b; or a buzzer sound emitted by an alarm buzzer 52c. Combinations of the above are also possible.
As noted, according to the ninth through eleventh inventions, a manned vehicle is informed of the relative positional relationship of itself and another vehicle, allowing the human operator of the manned vehicle (own vehicle) to ascertain before the fact the likelihood that, on the current course, the vehicles will interfere, for example, so that interference between the vehicles can be avoided.
In particular, visual display of the relative positional relationship of the own vehicle and the other vehicle on a display means affords better recognition of the relative positional relationship.
In the event of impending interference between vehicles, a warning to this effect is provided so that interference between the vehicles can be avoided.
According to the twelfth invention, the relative positional relationship of an own vehicle and other vehicle, as well as the range of movement of the other vehicle with which this positional relationship exists, are displayed by display means, allowing the operator to verify current and future positional relationships vis-xc3xa1-vis the other vehicle.